What type of cocoa powder? Natural or Dutch process?

I seem to do research on this every year because I always forget. This year I wrote it down after combing through the archives in the web. Dorie says that either will work, but she recommends Guittard Dutch processed cocoa for this recipe. Strangely the natural cocoa powder seems to make the dough more crumbly, though I do not know why that is. Maybe a food scientist can give insight about that. The short story is that you can use either type but may find the dough easier to work with if you use Dutch processed cocoa. Whatever you choose, use the best chocolate you can afford since it is the heart of this cookie. Good luck! This really is a winner of a recipe.

The recipe will work fine with either; by preference I'd use Dutch process myself but I wouldn't worry if I didn't have it. Hershey's also has a "special dark" that's a combination of the two.